`(4^2. 5.11)/(44.20)`

`=(4.11.4.5)/(4.11.4.5)`

`=1`

`(13.15.16)/(18.65.7)`

`=(13.15.16)/(2.3.3.13.5.7)`

`=8/21`

`(7.2.8.5^2)/(14.2.5)`

`=(14.2.4.5.5)/(14.2.5)`

`=4.5`

`=20`

`(2^3. 3^3. 5)/(3.2^3. 5^3)`

`=(2^3. 3.5.3^2)/(2^3. 3.5.5^2)`

`=(3^2)/(5^2)`

`=9/25`

**Quy đồng:

`(4^2. 5.11)/(44.20)=1=525/525`

`(13.15.16)/(18.65.7)=8/21=200/525`

`(7.2.8.5^2)/(14.2.5)=20=840/525`

`(2^3. 3^3. 5)/(3.2^3. 5^3)=9/25=189/525`

Giải:

a) \(\dfrac{5^3.90.4^3}{25^2.3^2.2^{13}}\) 

\(=\dfrac{5^3.5.3^2.2.\left(2^2\right)^3}{\left(5^2\right)^2.3^2.2^{13}}\) 

\(=\dfrac{5^4.3^2.2.2^6}{5^4.3^2.2^{13}}\) 

\(=\dfrac{5^4.3^2.2^7}{5^4.3^2.2^{13}}\) 

\(=\dfrac{1}{2^6}=\dfrac{1}{64}\) 

b) \(\dfrac{15^2.16^4-15^3.16^3}{12^2.20^3-20^2.12^3}\) 

\(=\dfrac{15^2.16^3.16-15^2.16^3.15}{12^2.20^2.20-20^2.12^2.12}\) 

\(=\dfrac{15^2.16^3.\left(16-15\right)}{12^2.20^2.\left(20-12\right)}\) 

\(=\dfrac{\left(3.5\right)^2.\left(2^4\right)^3.1}{\left(3.2^2\right)^2.\left(2^2.5\right)^2.8}\) 

\(=\dfrac{3^2.5^2.2^{12}}{3^2.\left(2^2\right)^2.\left(2^2\right)^2.5^2.2^3}\) 

\(=\dfrac{3^2.5^2.2^{12}}{3^2.5^2.2^4.2^4.2^3}\) 

\(=\dfrac{3^2.5^2.2^{12}}{3^2.5^2.2^{11}}\) 

\(=2\) 

c) \(\dfrac{2.3+4.6+14.21}{3.5+6.10+21.35}\) 

\(=\dfrac{2.3+2.3.2.2+2.3.7.7}{3.5+3.5.2.2+3.5.7.7}\) 

\(=\dfrac{2.3+2.3.4+2.3.49}{3.5+3.5.4+3.5.49}\) 

\(=\dfrac{2.3.\left(1+4+49\right)}{3.5.\left(1+4+49\right)}\) 

\(=\dfrac{2.3}{3.5}\) 

\(=\dfrac{2}{5}\) 

Chúc bạn học tốt!

Ta có:

\(\frac{\left(-2\right)^3.3^3.5^3.7.8}{3.5^3.2^4.42}=\frac{\left(-2\right).\left(-2\right).\left(-2\right).3.3.3.5.5.5.7.2.2.2}{3.5.5.5.2.2.2.2.2.3.7}\)

\(=\frac{\left(-2\right)}{1}=-2\)

bn ghi ro hơn ko 

sai de roi ban oi

làm gì có đề nào như vậy

^{kết quả là-6}

rút gọn được 5^3 và 7.8=42

còn (-2)^3.3^2/2^4=-3^2/2

\(\frac{\left(-2\right)^3.3^3.5^3.7.8}{3.5^3.2^4.42}=\)

\(-\frac{2^3.3^3.5^3.7.2^3}{3.5^3.2^4.2.3.7}=\)

\(-\frac{2^6.3^3.5^3.7}{2^5.3^2.5^3.7}=\)

\(-\left(2.3\right)=-6\)

\(\frac{\left(-2\right)^3.3^3.5^3.7.8}{3.5^3.2^4.42}\)

\(=\frac{\left(-2.3.5\right)^3.7.2^3}{3.5^3.2^4.6.7}\)

\(=\frac{\left(-30\right)^3.2^3}{3.5^3.2^4.6}\)

\(=\frac{\left(-60\right)^3}{3.125.16.6}\)

Làm nốt nhé

\(\frac{2^3.3^3.5^3.7.8}{3.2^4.5^3.14}=\frac{2^3.3^3.5^3.7.2^3}{3.2^4.5^3.2.7}\)

\(=\frac{2^6.3^3.5^3.7}{2^5.3.5^3.7}=\frac{2.3^2.1.1}{1.1.1.1}=2.3^2\)

\(=2.9=18\)

\(\frac{2^3.3^3.5^3.7.8}{3.2^4.5^3.14}=\frac{1.3^2.1.1.8}{1.2.1.2}=\frac{3.3.4}{2.1}=\frac{3.3.2}{1}=18\)

\(...=\frac{2^6.3^3.5^3.7}{2.^53.5^3.7}=18\)

\(\frac{2^3.3^3.5^3.7.8}{3.2^4.5^3.14}\)mk viết như vầy bn cố gắng hiểu nhé:.

2³.3³.5³.7.8/ 3.2⁴.5³.14

= 2³.3³.5³.7.8/3.2⁴.5³.7.2

=2³.3³.5³.8/3.2⁴.5³.2

=2³.3³.5³.2³/2⁴.2.5³

= 2³.2³.3³.5³/ 2⁴.2.5³

= 2⁶. 3³.5³/ 2⁵. 5³

= 2⁵.2.3³.5³/2⁵.5³

= 2.3³/1

^{= 2. 27/1}

^{= 54/1 = 54}

^{Thế nha bn, chúc bn học tốt!}